A traditional pick-up truck has a cargo box used to carry various cargo. Generally, the cargo box is covered by a tonneau cover which is releasably clamped to and extended above the cargo box, so as to protect the carried cargo from adverse weather and improve the aesthetic appearance of the pick-up truck. Tonneau covers can be classified into hard-top type and soft-top type, wherein the hard-top type tonneau cover has a hard top made of rigid material, such as metal, fiberglass or the like, while the soft-top type tonneau cover has a soft top made of flexible material, such as canvas, vinyl plastic or a weather-resistant fabric. Moreover, the tonneau cover can be designed to provide a foldable function to help a user to conveniently extend or store the tonneau cover.
Referring now to FIGS. 1, 2 and 3, schematic views of a traditional foldable tonneau cover system for a pick-up truck are illustrated, wherein a tonneau cover system 10 is used to cover a cargo box 21 of a pick-up truck 20, and the tonneau cover system 10 comprises a plurality of frame sections 11, 12, 13, a plurality of hinges 14, a plurality of clamps (not-shown) and at least one cover portion 15. The number of the cover portion 15 can be one or corresponding to that of the frame sections 11-13 (such as three). The cover portion 15 is made of flexible or rigid material, and can be suitably fixed on the corresponding frame sections 11-13. Each of the frame sections 11 is constructed by a plurality of frame members. One of the frame sections 11, 13 can be pivotally connected to another adjacent frame section 12 through two or more of the hinges 14, so that all of the frame sections 11-13 can be adjusted to an extended position or a storage position.
When the frame sections 11 are in the extended position as shown in FIG. 2, the frame sections 11-13 are horizontally extended on two side walls 22 and a tailgate 23 of the cargo box 21, and fixed thereon by the clamps, so as to cover an inner space of the cargo box 21. When the frame sections 11-13 are in the storage position as shown in FIG. 3, the frame sections 11-13 are folded and stacked on a front end of the two side walls 22, so as to expose the inner space of the cargo box 21 for placing or taking cargo.
In the tonneau cover system 10, each of the hinges 14 mainly comprises two hinge portions and a pivot axis, wherein each of the hinge portions is installed on frame members of one of the frame sections 11-13, while the pivot axis is pivotally connected between the two hinge portions. In order to prevent water leakage from the gap between any two adjacent frame sections 11-13, side surfaces of the frame members of the two adjacent frame sections 11-13 are provided with a pair of laterally-extending channels (unlabeled), wherein a sealing strip 16 is disposed in each of the laterally-extending channels, respectively. Thus, when the frame sections 11 are in the extended position as shown in FIG. 2, the two sealing strips 16 can be abutted against each other to provide a waterproof function for the frame sections 11-13. Furthermore, the external (or internal) side of each of the hinges 14 can be covered with another seal sheet (not-shown) to further enhance the waterproof function for the frame sections 11-13.
However, in a first case that a large-area elongated piece of the seal sheet is covered on the external side of the hinge 14, when the two adjacent frame sections 11-12 are folded and stacked with each other, it is easy to irregularly twist the seal sheet between two outer surfaces of the two adjacent frame members, and thus the ideal folding angle (i.e. 180 degree) between the two adjacent frame sections 11-12 may not be carried out due to the jam of the seal sheet. On the other hand, in a second case that a small-area elongated piece of the seal sheet is covered on the internal side of the hinge 14, when the two adjacent frame sections 11-12 are horizontally extended, it is still easy to irregularly twist the seal sheet between two side surfaces of the two adjacent frame members, and thus the ideal extension angle (i.e. 0 degree) between the two adjacent frame sections 11-12 may not be carried out due to the jam of the seal sheet; and when the two adjacent frame sections 11-12 are folded and stacked with each other, it is easy to generate a pull force between two outer surfaces of the two adjacent frame members because the curve length of the seal sheet may be insufficient, and thus the ideal folding angle (i.e. 180 degree) between the two adjacent frame sections 11-12 may not be carried out due to the insufficient curve length of the seal sheet.
Moreover, the pivot axis of the hinge 14 is installed at a fulcrum position between the two adjacent frame members, and thus occupies a certain space of the gap therebetween in the horizontally extended status. As a result, the pivot axis interfere with the installation and open/close operation of the seal sheet on the external or internal side of the hinge 14, so that it may increase the installation offset between the hinge 14, the seal sheet and the frame members. As a result, the installation yield may be affected, and the waterproof reliability thereof may be reduced.
As a result, it is necessary to provide a waterproof seal structure and a hinge structure for the foldable tonneau cover to solve the problems existing in the conventional technology, as described above.